Pool overwhelmed with algae, about to drain and refill

[punchclock]

Hello,
Proud to be finally posting to the best pool advice column on the planet! I've searched the site some, but still would like more input. Austin, TX, after 10 years of paying for chemicals, have maintained our own for about two years. Late in the season last year, algae began. CYA was 150, the SLAMMing was hard to keep up with, got close, then just recognized that I was wasting time and chemicals in a losing battle in a pool that I wouldn't use for 4 months anyway. Now, I've completely let it go over the winter. Probably not the 'best' way, but here I am.

Totally green, looks like mustard algae. Have had small black algae spots in the past, although it's so green now, I can't see any of the little spots.
FC=0
pH=7.8
CYA=110 (did some draining w/rainwater replacement over the winter)

Wastewater averaging period ends next week, so I'd like to drain and refill. Time for the questions:

1. What should I do before draining? Add algaecide and recirc? I know the general opinions here of algaecide, but this kinda falls under 'winterizing'.
2. Should I completely drain to minimize algae population, and allow for a thorough scrub down, or just enough to allow for CYA dilution?
3. Anything I should do regarding the sand (last changed 10 years ago)?
4. When refilling, should I follow the standard order for rebalancing chemicals, or is there special considerations because of the massive algae growth? I never want the CYA to get this high again, and I unwisely have an overstock of chlorine stabilized tri-chlor pucks. I guess I'll use those to get CYA to 40 or so, then convert to liquid chlorine.

Looking forward to recs from a group of REAL experts who aren't trying to sell me into a silly vicious cycle of unnecessary chemicals.

Thanks!
punchclock

 

[Bperry]

Hello,
Proud to be finally posting to the best pool advice column on the planet! I've searched the site some, but still would like more input. Austin, TX, after 10 years of paying for chemicals, have maintained our own for about two years. Late in the season last year, algae began. CYA was 150, the SLAMMing was hard to keep up with, got close, then just recognized that I was wasting time and chemicals in a losing battle in a pool that I wouldn't use for 4 months anyway. Now, I've completely let it go over the winter. Probably not the 'best' way, but here I am.

Totally green, looks like mustard algae. Have had small black algae spots in the past, although it's so green now, I can't see any of the little spots.
FC=0
pH=7.8
CYA=110 (did some draining w/rainwater replacement over the winter)

Wastewater averaging period ends next week, so I'd like to drain and refill. Time for the questions:

1. What should I do before draining? Add algaecide and recirc? I know the general opinions here of algaecide, but this kinda falls under 'winterizing'.
2. Should I completely drain to minimize algae population, and allow for a thorough scrub down, or just enough to allow for CYA dilution?
3. Anything I should do regarding the sand (last changed 10 years ago)?
4. When refilling, should I follow the standard order for rebalancing chemicals, or is there special considerations because of the massive algae growth? I never want the CYA to get this high again, and I unwisely have an overstock of chlorine stabilized tri-chlor pucks. I guess I'll use those to get CYA to 40 or so, then convert to liquid chlorine.

Looking forward to recs from a group of REAL experts who aren't trying to sell me into a silly vicious cycle of unnecessary chemicals.

Thanks!
punchclock

Algaecide is useless once algae is there. It’s a preventative. Proper chlorination is also a preventative and it will also get rid of algae so it’s a better option.

Really the big reason to drain is to get your CYA down and get rid of as much algae as possible. It you better be ready to start the SLAM process once that’s done or it’ll just go back to what it was. Make sure you have the TF test kit beforehand.

 

[Dirk]

Just some random thoughts, not a comprehensive instruction set.

First, welcome to TFP. You're in the right place!

You'd need to drain about 64% of your water to get from CYA 100 down to 40. You could first drain 64% and then observe the walls. Would they benefit from a scrub? Then maybe drain the rest of the way. If not, then maybe not (depending on the cost of water).

If you do scrub, do not be tempted to use acid for that. Elbow grease is best, or a chlorine solution. Using acid is just going to compromise your plaster (as in, remove some of it).

You're going to have to SLAM. Read up on that and understand it thoroughly. You cannot skip steps or skimp on a SLAM. You'll just have to redo it. Have plenty of chlorine on hand, or make sure your supply source does. Be sure they have a fresh supply, not last years dregs. This time of year its hit or miss on that. Last years chlorine would likely be greatly reduced in strength.

Be sure you have plenty of Taylor reagents for the SLAM process. You might stock up on the FAS-DPD stuff. What you don't want is to run out of chlorine or the reagents mid-SLAM. The more often you test and dose, the faster your SLAM will be over. Stalling out mid-SLAM could send you right back to the beginning.

Sorry, I don't know enough about sand to advise. But you'll be back-washing often during the SLAM. Others can advise.

Nothing to do with all those pucks except to use them whenever CYA is low, or sell them.

 

[punchclock]

Just some random thoughts, not a comprehensive instruction set.

First, welcome to TFP. You're in the right place!

You'd need to drain about 64% of your water to get from CYA 100 down to 40. You could first drain 64% and then observe the walls. Would they benefit from a scrub? Then maybe drain the rest of the way. If not, then maybe not (depending on the cost of water).

If you do scrub, do not be tempted to use acid for that. Elbow grease is best, or a chlorine solution. Using acid is just going to compromise your plaster (as in, remove some of it).

You're going to have to SLAM. Read up on that and understand it thoroughly. You cannot skip steps or skimp on a SLAM. You'll just have to redo it. Have plenty of chlorine on hand, or make sure your supply source does. Be sure they have a fresh supply, not last years dregs. This time of year its hit or miss on that. Last years chlorine would likely be greatly reduced in strength.

Be sure you have plenty of Taylor reagents for the SLAM process. You might stock up on the FAS-DPD stuff. What you don't want is to run out of chlorine or the reagents mid-SLAM. The more often you test and dose, the faster your SLAM will be over. Stalling out mid-SLAM could send you right back to the beginning.

Sorry, I don't know enough about sand to advise. But you'll be back-washing often during the SLAM. Others can advise.

Nothing to do with all those pucks except to use them whenever CYA is low, or sell them.

Thank you for the advice-particularly about stocking up on reagents and chlorine stock degradation. I'm anticipating a full drain once the algae on the sides starts showing reveals the need for full scrub down--bleach and elbow grease only. After the last SLAM (that was close, prior to a one-week vacation) I'm picking a couple of weeks when I have plenty of time to stick with it.

 

[punchclock]

Algaecide is useless once algae is there. It’s a preventative. Proper chlorination is also a preventative and it will also get rid of algae so it’s a better option.

Really the big reason to drain is to get your CYA down and get rid of as much algae as possible. It you better be ready to start the SLAM process once that’s done or it’ll just go back to what it was. Make sure you have the TF test kit beforehand.

Thanks for the help. I definitely will work with proper chlorination this season, after last seasons disaster that was at least in part due to using trichlor and letting CYA make the shock process more difficult. Lots of wasted gallons of chlorine.

 

[Dirk]

Thanks for the help. I definitely will work with proper chlorination this season, after last seasons disaster that was at least in part due to using trichlor and letting CYA make the shock process more difficult. Lots of wasted gallons of chlorine.

This is why we that have them rave about SWGs (Saltwater Chlorine Generators). Once installed and adjusted, your chlorine is made fresh and delivered to the pool as needed. FC is maintained with minimal effort.

The math used to work out, where the cost of an SWG over time equaled the cost the liquid chlorine you would have to buy instead. I don't know how well that still stands, but when you add in the expenses of water exchanges and chlorine waste, the cost of the two MOs of chlorination cannot be too far off.

I haven't had algae since I installed one. I wouldn't own a pool without one. I could safely guess that most of us SWG owners can say the same. Something to think about...

 

[Newdude]

The math used to work out, where the cost of an SWG over time equaled the cost the liquid chlorine you would have to buy instead. I don't know how well that still stands,

For most these days it's 2X cheaper to pay for a full SWG install. (When properly oversized). Replacement cells that don't need the install or the controller can get between 4X and 8X the cost of chlorine, FC for FC.

 

[Dirk]

For most these days it's 2X cheaper to pay for a full SWG install. (When properly oversized). Replacement cells that don't need the install or the controller can get between 4X and 8X the cost of chlorine, FC for FC.

Holy cow! I know the cost of SWGs has gone up significantly. So that must mean the cost of chlorine has gone way, way up.

When you factor in the convenience and the FC stability factors we've been discussing in this thread, an SWG is a no brainer.

If I may, @Newdude, can I reword your post, to confirm I read it right?

In most situations:

The cost of the chlorine produced by a properly oversized SWG (that's the installation cost of the SWG transformer and cell) during its lifespan, can be half as much as the cost of the same amount of liquid chlorine purchased at a store.

The cost of the chlorine produced by a SWG replacement cell (this is after the first cell wears out), can be 1/8 to 1/4 as much as the cost of the same amount of liquid chlorine purchased at a store.

 

[Newdude]

A 2x cell produces about 1000 jugs worth of FC which is well over $6k for most of us. ($5.67 + tax at WM).

You could spend $4k on installing the first cell and make 50% of your money back.

For smaller pools with the ability to go 3X-5X they can really clean up because the upgrade cost doesn't reflect the extra production/ lifespan.

 

[punchclock]

This is why we that have them rave about SWGs (Saltwater Chlorine Generators). Once installed and adjusted, your chlorine is made fresh and delivered to the pool as needed. FC is maintained with minimal effort.

The math used to work out, where the cost of an SWG over time equaled the cost the liquid chlorine you would have to buy instead. I don't know how well that still stands, but when you add in the expenses of water exchanges and chlorine waste, the cost of the two MOs of chlorination cannot be too far off.

I haven't had algae since I installed one. I wouldn't own a pool without one. I could safely guess that most of us SWG owners can say the same. Something to think about...

Great advice! I think our plan is to do a big re-do of the pool (plaster, tiling, coping) next fall/winter. I hadn't really considered a SWG, but this may be something that we roll into that project. Actually, based on the cost and time involved with getting chlorine, it's creeping towards something we 'will' do instead of 'may' do.

 

[Lake Placid]

I didn't see anyone adress the sand question so I'll chime in. Don't worry about your media/filter unless you have turbidity and all other chemistry issues are confirmed to be in spec. If that is indeed the case then I would investigate if the filter is low on media and needs to be topped up or look for a broken lateral etc. 90% of the time cloudy water or turbidity is caused by lack of sanitation or another factor being off in the water chemistry.

 

[wireform]

Here's my take. Redoing the pool plaster next winter is perfect but I'd still go for the SWCG this season. Doesn't look like you have automation so a circupool SWCG for you is a no brainer. If you're a diy'er then you can get lots of help here. About the sand filter you should do a deep cleaning as sand doesn't go bad and need to be exchanged only when certain potions are used and ruin the sand.
Deep Cleaning a Sand Filter

 

[punchclock]

I didn't see anyone adress the sand question so I'll chime in. Don't worry about your media/filter unless you have turbidity and all other chemistry issues are confirmed to be in spec. If that is indeed the case then I would investigate if the filter is low on media and needs to be topped up or look for a broken lateral etc. 90% of the time cloudy water or turbidity is caused by lack of sanitation or another factor being off in the water chemistry.

Thanks for the advice. I haven't had turbidity issues, and honestly, having changed the sand before, I'd like to avoid that project. Sounds like I can for now.